More than 10 per cent of coronavirus victims are infected by someone who has the virus but does not yet have any symptoms, a global team of scientists have found.
And they say this backs measures to curb socialising such as going to pubs, cafes and restaurants.
They say this is the first research to prove that the disease can be spread by people who are not showing any symptoms and helps to explain the rapid infection rate.
The research comes as hundreds of thousands of people are self-isolating and practising social distancing in an attempt to flatten the rate of infection.
The team from the United States, France, China and Hong Kong found the time between a person infecting another is less than a week.
Researchers found that the average serial interval for the novel coronavirus in China was approximately four days.
This also is among the first studies to estimate the rate of asymptomatic transmission.
The researchers from the University of Texas at Austin said the short "serial interval" of COVID-19 means the outbreak is difficult to stop.
Lauren Ancel Meyers, a professor of integrative biology, said: "Ebola, with a serial interval of several weeks, is much easier to contain than influenza, with a serial interval of only a few days.
"Public health responders to Ebola outbreaks have much more time to identify and isolate cases before they infect others.
"The data suggest that this coronavirus may spread like the flu. That means we need to move quickly and aggressively to curb the emerging threat."
Previously, researchers were unsure whether people without symptoms could transmit the virus.
But now they are sure more than 1 in 10 infections from 450 infection case reports in China were from people who had the virus but did not yet feel sick.
Dr Meyers said: "This provides evidence that extensive control measures including isolation, quarantine, school closures, travel restrictions and cancellation of mass gatherings may be warranted.
"Asymptomatic transmission definitely makes containment more difficult."
She added: "Our findings are corroborated by instances of silent transmission and rising case counts in hundreds of cities worldwide.
"This tells us that COVID-19 outbreaks can be elusive and require extreme measures."
The study was published in the journal Emerging Infectious Diseases.
